A081424 - OEIS

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A081424

Class 5- primes (for definition see A005109).

283, 359, 557, 659, 941, 1109, 1129, 1223, 1433, 1663, 1669, 1693, 1787, 1997, 2027, 2039, 2069, 2083, 2153, 2339, 2351, 2503, 2539, 2579, 2633, 2767, 2777, 2803, 2837, 2999, 3229, 3581, 3761, 3767, 3779, 3989, 4127, 4157, 4231, 4253, 4283, 4297, 4513

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OFFSET

1,1

REFERENCES

R. K. Guy, Unsolved Problems in Number Theory, A18.

LINKS

R. J. Mathar, Table of n, a(n) for n = 1..20000

MATHEMATICA

PrimeFactors[n_Integer] := Flatten[ Table[ #[[1]], {1}] & /@ FactorInteger[n]]; f[n_Integer] := Block[{m = n}, If[m == 0, m = 1, While[ IntegerQ[m/2], m /= 2]; While[ IntegerQ[m/3], m /= 3]]; Apply[Times, PrimeFactors[m] - 1]]; ClassMinusNbr[n_] := Length[NestWhileList[f, n, UnsameQ, All]] - 3; Prime[ Select[ Range[700], ClassMinusNbr[ Prime[ # ]] == 5 &]]

CROSSREFS

Cf. A005113, A056637, A005109, A005110, A005111, A005112, A081425, A081426, A081427, A081428, A081429, A081430.

Sequence in context: A175276 A334096 A142937 * A142699 A113157 A142446

Adjacent sequences: A081421 A081422 A081423 * A081425 A081426 A081427

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Mar 20 2003

STATUS

approved